EUREKA, Calif. — A powerful offshore earthquake rattled communities in far northern California, cutting power to thousands of customers, causing minor damage to homes and businesses and forcing many people to seek treatment for cuts and bruises from falling debris.

The 6.5 magnitude temblor hit at about 4:27 p.m. PST Saturday and was centered in the Pacific about 22 miles west of Ferndale, but was felt as far south as Capitola in central California and as far north as central Oregon, the U.S. Geological Survey said.

In Eureka, about 240 miles north of San Francisco, residents of an apartment building were evacuated, and an office building and two other commercial structures were declared unsafe for occupancy, according to Humboldt County spokesman Phil Smith-Hanes.

"Our initial reports were that, though this was a pretty decent quake, we survived it well," Smith-Hanes said, adding that damage assessments would continue on Sunday across the county.

More than a dozen aftershocks, some with magnitudes as powerful as 4.5, rumbled for several hours after the initial quake, which had a depth of nearly 10 miles.

Broken glass
Authorities said no major injuries have been reported. But several people received minor cuts and scrapes from broken glass at the Bayshore Mall in Eureka, and an elderly person fell and broke a hip, authorities said.

"We're mostly getting reports of bumps, bruises and hits on the head," said Laurie Watson Stone, a spokeswoman for St. Joseph Hospital, a 146-bed hospital in Eureka. "The emergency room is busy, but we haven't heard of any major injuries."

Amanda Nichols, a dispatcher for Eureka Police Department, said she received a report that an infant was struck in the head with some flying debris at the mall.

Lisa Caldwell, of Eureka, described the quake as "one of the most violent ... in my 43 years of living in California." She said her neighborhood was left without power for more than seven hours.

Amber Jackson, another Eureka resident, told msnbc.com that she had just put her son into her Jeep when they "felt a little shake".

"My friend and I looked at each other and more small rolling started," said. "Luckily the door to the Jeep was open, I snatched my 7-year-old old son ... and all three of us ran into the middle of the street.

"We watched as the poles swayed back and forth and the noise was deafening! My son was so scared — he kept trying to run. I had to hold him as tight as I could and try to keep our balance. Down the road a neighbor's porch collapsed and broke a gas line."

Virginia Resanda said she was visiting a doctor's office in Eureka when the she felt the tremors.

"It shook, swayed, and then slapped our building," she told msnbc.com. "It was a very strong quake."

Pacific Gas & Electric Co. spokesman J.D. Guidi said power outages were widespread across most of Humboldt County, affecting about 25,000 customers.

About 3,400 remained without power some eight hours after the quake, NBC News reported. Some could remain without power through Sunday, PG&E spokeswoman Janna Morris said.

No damage was done to the company's former nuclear power plant outside Eureka, Morris said.

"People have chimneys down, and we're hearing about minor property damage and lots of glassware broken," Wattle said. "People are really shaken up. It was shaking pretty good, then it had a big jolt to it at the end."

Police in Ferndale, several miles south of Eureka, said the earthquake caused stucco to fall off City Hall and broke shop windows, strewing the historic downtown streets with glass shards.

"I thought a tire had blown off my truck because it was so hard to keep control of the vehicle," Officer Lindsey Frank said. "Power lines were swaying, and I could see people in the fields trying to keep their balance."

Eureka city spokesman Gary Bird said because the earthquake hit shortly before dark, only the city's old town received thorough surveys for damage. Authorities there found fallen bricks and parapets that had fallen off old structures, causing damage to adjacent buildings, he said.

"There are some frayed nerves, but I think we've come through this pretty well for the magnitude of earthquake we've had," Bird said.

Televisions tumbled and objects were knocked off walls in Arcata, a small town that's home to Humboldt State University, one resident said.

"The whole town is kind of freaked out right now," said Judd Starks, the kitchen manager at a bar and restaurant known as The Alibi. "All the power is out, people are out walking around."

"Pictures were banging against the walls, I was frightened!" she added. "The shaking seemed to lessen then took off again. I could feel the walls sway and the hanging light fixtures were swinging to where they almost touched the ceiling. It seemed like minutes, but in reality was probably only 30 seconds."

It struck in an area where earthquakes ranging from 7.0 to 7.3 have struck periodically since the 1800s, causing damage and injuries.

California is one of the world's most seismically active regions. More than 300 faults crisscross the state, which sits atop two of Earth's major tectonic plates, the Pacific and North American plates. About 10,000 quakes each year rattle Southern California alone, although most of them are too small to be felt.

'Extremely unsettling'
The damage created by an earthquake depends greatly on where it hits. A 7.1 quake — much stronger than Saturday's 6.5 temblor — hit the Mojave Desert in 1999 but caused only a few injuries and no deaths.

By contrast the 1994 Northridge earthquake under Los Angeles' San Fernando Valley was magnitude 6.7. It killed 72 people, injured more than 9,000 and caused $25 billion in damage in the metropolitan area. And the magnitude-7.1 quake in October 1989 struck just before the third game of the World Series at Candlestick Park. The quake, centered in the Santa Cruz Mountains on the San Andreas fault, caused nearly $3 billion in damage.

Dan Bowermaster of San Francisco was with relatives in Eureka when Saturday's quake hit, moving the refrigerator in his cousins' home about 3 feet. He said he had been in several moderate and large quakes throughout California, but had never felt anything as strong as this one.

"It was extremely unsettling. It was shaking in kind of a circular way," he said.

Sandra Hall, owner of Antiques and Goodies in Eureka, said furniture fell over, nearly all her lamps broke and the handful of customers in her store got a big scare. She said it was the most dramatic quake in the 30 years the store has been open.

"We'll be having a sale on broken china for those who like to do mosaics," she said.

NBC News, The Associated Press and msnbc.com staff contributed to this report.

Video: More aftershocks

Closed captioning of: More aftershocks

>>>now to that 6.5 magnitude earth wake that rattled far
northern california
saturday. they're still feeling the aftershocks this morning as officials try to assess the damage. garvin from kntv is up in eureka, california, with the latest. good morning.

>>reporter: good morning,
lester
. even by california standards this part of the state gets more than its
fair share
of earthquakes but even for earthquake veterans, yesterday's was pretty scary. we'll show you some of the damage in old town eureka. you see that old brick building. part of the side has crumbled away. much more typical damage right across the street in a back store downtown on
2nd street
. they're going to have a lot of work today cleaning up all that stuff that's fallen off the shelves. let's get to the latest numbers on this. we've had more than a dozen aftershocks since the 6.5, including one of 4.1 that we felt just within the past two hours. damage, as you can see, mostly
broken windows
, things off store shelves and off walls, no serious injuries but a number of people have
head injuries
from things falling on their heads. people experience a lot of earthquakes, they said when this one started yesterday, they said just another earthquake. as it got stronger, up to 6.5 and lasted longer, as long as 30 seconds, people said they really got freaked out. more than one person told us they thought this was the end for them. and
power outage
is a problem in earthquake. from a peak of 25,000 without power yesterday, the local utility company has whittled that down to only about 3400 people.
lester
, they say they expect to have all them back online sometime today.